Evidence for a genetically distinct population of Exobasidium sp. causing atypical leaf blight symptoms on lowbush blueberry (Vaccinium angustifolium Ait.) in Newfoundland and Labrador, Canada

The genus Exobasidium includes a number of species that are pathogenic to members of the Ericales, including blueberries (Vaccinium spp.), and Exobasidium leaf spot is an emerging concern for commercial blueberry production. Atypical Exobasidium leaf spot-like symptoms were observed in wild V. angustifolium (lowbush blueberry) in eastern Newfoundland and Labrador, Canada, beginning in 2016. A fungus with morphological characteristics typical of Exobasidium spp. was isolated from symptomatic tissue. The ITS regions from five isolates, and the LSU regions from two, were sequenced and compared with publicly available Exobasidium spp. sequences, including from E. maculosum, cause of Exobasidium leaf spot on V. angustifolium. The isolates collected in this study were genetically distinct from all isolates of E. maculosum, as well as from the other Exobasidium spp. sequences available, suggesting that the isolates described here represent a genetically distinct population belonging to the genus Exobasidium.